A three-electrode potentiostat is a widely-used electronic circuit used in sensor devices to analyze electrochemical and biochemical cells in the chemical industry, health industry and biology industry. The three-electrode potentiostat controls potentials of two electrodes and senses the current flowing through a third electrode. Depending on the applied potential difference across the two electrodes and the concentration of the electrochemical cell, a certain amount of cell current sinks into and/or out of the third electrode. Since the output current is very small (such as tens of nanoamperes or less) and the offset voltage may cancel out the small amount of current, the offset needs to be very small.
Moreover, for a large biosensor array including several potentiostats in a one microchip, the offset variation between the potentiostats tends to deteriorate the sensing accuracy. Thus, the offset variation needs to be tiny.
Conventional potential control schemes for potential deviation suppression are costly and time consuming and may fall within one of three conventional methods: a floating-date transistor method, a back-gate tuning method and a correlated double sampling method. The floating-date transistor method and the back-gate tuning method are expensive, have high silicon area requirements and are time consuming. The correlated double sampling method disadvantageously generates a large potential swing.
Thus, what is needed is a quick, inexpensive method for accurately controlling potentials in a potentiostat circuit which at least partially overcomes the drawbacks of present approaches and provides improved silicon real estate requirements, time consumption and reduced potential swing. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background of the disclosure.